Air cooled grate



March 29, 1932. A, U JR 1,851,425

AIR COOLED GRATE Filed March 1, 1929 2 Sheets-Sheet 1v //VVENTOR Andrew640/, Jr.

' /47TORNEY March 29, 1932. A. GAUL. JR

AIR COOLED GRATE 2 Sheets-Sheet 2 Filed March 1, 1929 Hlil II I

ATTORNEY A a forced draft may be used if Patented maze, 1932 ANDREWGAUL, .13., or Armin; new YORK AIR coonnn i-RATE Application filedltarch1,

My invention relates to grates for burning coaland particularly togrates for burning very fine coal, such as No. 1 buckwheat and smaller,without a forced draft, although desired.

, Grates of the ordinary type used for burning coal in larger sizes arenot adapted for burning coal of the buckwheat and smaller sizes becausethe spacing between the, grate 10 bars is so great that the finercoaldrops through into the ash pit. When the spacing of the grate barsis decreased so that the coaldoes not fall through, the available spacefor the passage of air is cut down to such an extent that the 'coalcannot be burned without a forced draft. \Vhen both the spacing andthickness of bars of the present types are reduced, the grate, becauseof its comparatively delicate structure burns and warps unless kept coolby some forced draft. For these reasons, it has not been practicable toburn buckwheat or finer coal with a natural draft in residences havingchimneys ofordinary height. Furthermore, the maximum volume of air whichit is possible to pass through grates of the present type adapted forburning the finer sizes of coal is insuflicient to provide the high rateof combustion which,

in many instances, is desired.

One of the objects of my invention, therefore, is to provide a gratewhich will satisfactorily and economically burn the finer sizes ofcoalwithout a forced draft and with a chimney of ordinary residentialheight. Another I character that when used with forced draft or induceddraft such as in a locomotive, steam vessel or industrial plant, thesefiner sizes of coal may be burned at a much higher rate than is nowpossible with present type grates. Another ObJGOt'lS to provide agrateof this character having substantially no surfaces upon or betweenwhich ashes may accumulate. Another incidental object is to provide agrate for a furnace having a circular fire pot in which there will be noopenings of such a,

large size that fine particles of coal can fall therethrough into theash .pit. Another object is to provide a grate having a minimum amountof metal therein and having this object is to provide a grate of such1929. Serial N0. 343,657.

.of'the type now used. Another object is to provide a grate which, whileparticularly adapted to burn extremely fine coal, is also adapted toburn coal of any size and may be shaken or turned in such a way as to.provide openings sufliciently large for the passage of any stones,clinkers or ,cind'ers present in the fire pot. And a further object isto .pro-

vide a grate throu h volume of air may than with grates of the presenttype.

I accomplish these objects by the means and in the manner described inthe following which a much greater e passed in a. given timespecification and illustrated in the accompan'ying drawings in which--ig. 1 is a plan view of my grate adapted for a furnace having a roundfire box Fig. 2 is a section of Fig. 1 inthe plane 2- Fi 3 is a sectionof Fig. 1 in the plane 3-3 1 4 is a section ofFig. 1 in the plane 9 IFig. 5 illustrates my grate as adapted for a furnace having arectangular fire box;

Fig. 6 is a section of Fig. 5 in the plane 66; and

Fig. 7 is a fragmentary perspective view of a section of a stationarygrate. Referring to the drawings, my grate, when circular or square,prefera ly comprises four sections carried by the supporting bars, 1, 2,

3 and- 4, and assembled upon which, or preferably cast integraltherewith, are the fins represented generally in Figs. 1, 2, 3 and 4, bythe numeral, 5. and'in Figs. 5 and 6 by the numeral, 5'.. -Where thegrates are to be used with a furnace having a rectangular fire box, allof the fins may be similar, as

shown in Figs, 5 and 6. In either the round or rectangular species ofgrate, these fins are space occupied by the fins,

extremely thin plates of metal, and preferably but not necessarilydecrease in thickness from the top to a comparatively sharp edge havingno substantial thickness at the bottom. Thefins in any case arecomparatively deep so that the sides of each present heat radiatingsurfaces of substantial area to the incoming air. The supporting barsare of course round where they pass through the sides of the fire box sothat they may be turned in shaking, but the cross section, within the ispreferably quite steeply sloped upon the top as shown in Figs. 3 and 6so that ashes will not rest thereon. It will also be noted that the bars1, 2, 3 and 4, and the bars, 1, 2, 3 and 4. are spaced at the top willreadily fall somewhat below the upper edges of the fins.

The fins should in all instances, be very thin at the top, for example,not over one-fourth inch, and preferably one-eighth of an inch orslightly less in thickness, and the clear spaces between the bars, atthe top, should always be substantially wider than the thickness of thebars thus assuring a ratio of. air space to metal in excess of 1 to 1.Where-No. 1 buckwheat, for example, is to be burned, it has been foundin practice that fins oneeighth of an'inch thick at the top and spacedas wide as five-sixteenth of an inch will give highly satisfactoryresults. In this case, if the fins are tapered the spaces between thefins at the bottom are about seven-sixteenths of an inch'so that ashespassing the spaces through when the grate is agitated and will notbecome clogged between the fins.

main elements,

- gether,

Where the grate is intended for use with a furnace having a rectangularfire box there may be as many separate elements as are necessary, andeach element of the grate as well as the fins may be alike, as shown inFig. 5. Where the grate is intended for use in a circular fire box eachone of the grate elements is necessarily different. In the latter case,the outer edges of the fins associated with supporting bars, 1 and 4,are arranged in a circular areas are also the edges of several of thefins at each end of bars, 2 and 3. As shown in Figs. 1, 2 and 4, theextreme fins at each end of the supporting bars, 2 and 3, are providedwith projections, 7, disposed at right angles to the end fins so that nolarge space remains here between the grate and fire pot. The spaces, 6,between the separate sections of the grate should, of course, conformsubstantially to the spacing of the fins.

Where the grates consist of four separate, as shown in Figs. 1 and 5,the usual gear wheels, 8 and 9, which mesh toand 10 and 11, which meshtogether, are provided on the front ends of the supporting bars. Bars, 2and 3, are also squared at the ends, as shown at 12, to receive a shakerhandle.

The particular configuration of the fins is able grate not important butwhere a grate of the rocking type is to be provided, the fins, below theplane of the fire, must be of such shape as to provide the necessaryclearance in dumping or shaking. For this reason, and because it ispreferred to .keep the metal content as low as possible, the best formof fin is believed to be approximately triangular and about in theproportions shown. 1

By making the fins extremely thin, and thinner than the spaces between,it is possible to provide a grate having an unusually large air surfaceas compared to the metal surface in the plane of the top of the grate.\Vhere the grates are made to the dimensions mentioned above as suitablefor burning No. 1 buckwheat, the air surface is practically 75% of totalgrate surface and the metal area is only 25%. In other words, there isthree times as much air as metal. This makes it quite possible to burnvery fine coal with the natural draft available in the chimney of theordinary dwelling. Furthermore, the extremely high radiation from thefins serves to preheat the air fed to the fire and some increasedefliciency in combustion is attained in this way.

By making the fins extremely thin and very deep to provide largeheat-radiating or cooling surfaces, all warping or burning of the grateis avoided, and although such a grate is rather delicate in appearanceit is, 011 account of its relatively great depth, in fact extremelydurable and serviceable.

By-gearing the supporting bars together, as illustrated, it is obviouslypossible to move the grate elements so that comparatively large spacesare opened between them. It will be apparent, therefore, that such agrate is in nowise limited to burning a fine size of coal, and whileparticularly adapted for the smaller sizes of coal may be used with anyfuel of any size.

In many instances Where the ashes are removed by raking instead ofshaking a movis not essential. In such cases a design similar to thatshown in Fig. 7 may be used. Here, atively long and substantiallyrectangular when viewed from the side. They are preferably tapered tosubstantially no thickness at the bottom and are made deep enough towithstand the vertical load thereon when considered as beams, as well asto provide large the bars or fins are comparpreferred embodiment it isto be understood that the illustrations are typical only and that thewords which I have used are words of description rather than oflimitation, and that changes, within the purview of the appended claims,may be made without departing from the true scope and spirit of myinvention in its broad aspects.

What I claim is l. A grate for burning coal of the finer sizes, such asbuckwheat, without material loss by falling through, comprisin aplurality of parallel, very thin but deep s having theirmaximumthickness at the topto form a supporting surface for the fuel, andcharacterized by having said fins closely spaced in the plane of the topbut having the thickness of said fins in said plane less than the spacebetween said fins in said plane whereby the minimum aggregate crosssectional area of the air spaces substantially exceeds the maximumaggregate cross sectional area of metal throughout the grate.

2. A grate for burning coal of the finer sizes, such as buckwheat,without material loss by falling through, comprising a plurality ofparallel bars provided with very thin but deep transverse fins havingtheir maximum thickness at the top to form a supporting surface for thefuel, and characterized by having said fins closely spaced in the planeof the top but having t e thickness of said fins in said plane 'lessthan the space be- I tween said fins in said plane whereby the minimumaggregate cross sectional. area of grate is rocked; and said grate beingcharacterized by having said fins closely spaced in the plane of the topbut having the thickness of said fins in said plane less than the spacebetween said fins in said plane; whereby the minimum aggregatecross'sectional area of air spaces substantially exceeds the maximumaggregate cross sectional area of metal throughout the grate.

ANDREW GAUL, JR-

air spaces substantially exceeds the maximum aggregate'cross sectionalarea of metal throughout the grate.

3. grate for burning coal of the finer sizes, such as buckwheat, withoutmaterial loss' by falling through, comprising a plurality of parallelbars provided with very thin but deep transverse fins cast integraltherewith and having their maximum thickness at the top to form asupporting surface for the fuel, and characterized by having said finsclosely spaced in the plane of the top but having the thickness of saidfins in said plane less than the space between said fins in said planewhereby the minimum aggregate cross a sectional area of air spacessubstantially exceeds the maximum aggregate cross sectional area ofmetal throughout the grate.

.4. A rocking grate for burning coal of the finer sizes, suchasbuckwheat, without substantial loss b falling through, comprising aplurality o rotatably mounted, parallel, supporting bars provided with amultiplicity of very thin but deep transverse fins decreasing both inwidth and thickness from a maximum at the top and forming a supportingsurface for the fuel; said fins havin comparatively sharp, knife-likeedges w ereby clinkers arecut and broken up when the

